This achievement is unlocked by starting the wizard mode on Medieval Madness. To unlock the mode, you must:
Complete the ramps, orbits, and catapult 3 times each.
Defeat 10 trolls.
Destroy 6 castles.
Once the mode is unlocked, shoot the ball into the castle for your achievement.
If you wish to use wizard powers, run rewind in case of early ball drains.
For the trolls, clear the mode then start Multiball Madness. Trolls hit during this mode count towards the total.
During Royal Madness, the first successful shot on ramps, orbits, and the catapult will auto complete 1 cycle, try and start the mode when you’ve already done 2 cycles of each.
For the catapult, if you receive a “Bam”, then that counts as 2 shots except when there’s 2 already done. Also you can reshoot items.
Finally, shooting the castle during multiball let’s you skip the castle destruction scene and runs less risk of a drain.